Communication is 7% words, 38% vocal and 55% visual. So, if on the phone, you do not receive the 55% visual. If via email, you lose out on the visual and vocal, and only receive the 7% words. This leads to more room for misunderstanding, and humor becomes very challenging.
Emails are transactional, not relational. When discussing the latter, which many do…there are issues because there is no tone/body language (Emoticon does not count as relational!).
A friend who works at the Federal Reserve has this email guidance: Bottom Line Up Front. She told her staff to state the request at the beginning of the email, and then use the rest of the email to support the request. This expedites the reading/scanning of emails.
An Air Force General told me that because all digital communications are discoverable, he has 3 email responses and never types in more than this: “thanks”, “got it”, and “come see me.”
Are you an effective email communicator?